MULTINUCLEAR NMR-STUDIES OF WATER IN SOLUTIONS OF SIMPLE CARBOHYDRATES .1. PROTON AND DEUTERIUM RELAXATION

The dependence of water proton and deuterium transverse relaxation rates on pulse spacing is used to investigate the hydrogen exchange kinetics and water reorientational dynamics in glucose solutions over a wide concentration range. A complementary T1-rho dispersion analysis is also undertaken. The results show that within the pH range 4-8 proton exchange between glucose and water occurs primarily by a non-ionic, cyclic transfer mechanism involving the interaction of two water molecules per glucose hydroxyl group. Interaction with the glucose introduces a slight anisotropy into the reorientational motion of the water. The two correlation times characterizing this anisotropic motion are estimated from the deuterium relaxation data. Similar phenomena are expected in all aqueous carbohydrate systems having accessible hydroxyl groups.